Pesticide use and pesticide-related symptoms among black farmers in the Agricultural Health Study

BACKGROUND: Health effects of pesticides have not been well studied in black farmers. We describe agricultural practices and pesticide-related symptoms in North Carolina black and white farmers participating in the Agricultural Health Study. METHODS: Self-administered questionnaires were completed by 891 black and 11,909 white farmers licensed to apply restricted pesticides. Regression models were used to compare characteristics by race. RESULTS: Black farmers reported lower lifetime pesticide use, less use of each class of pesticides (e.g., herbicides, insecticides), less use of high exposure application methods, and fewer pesticide-related symptoms such as headaches or dizziness, skin irritation, chest discomfort and feeling nervous or depressed than did white farmers. CONCLUSIONS: Differences between black and white farmers may be explained by farm characteristics or economics. Despite lower use of pesticides, black farmers may have other work practices that affect exposure and risk.     

Lifetime Pesticide Use and Telomere Shortening among Male Pesticide Applicators in the Agricultural Health Study

Background: Telomere length (TL) in surrogate tissues may be influenced by environmental exposures.Objective: We aimed to determine whether lifetime pesticides use is associated with buccal cell TL.Methods: We examined buccal cell TL in relation to lifetime use of 48 pesticides for 1,234 cancer-free white male pesticide applicators in the Agricultural Health Study (AHS), a prospective cohort study of 57,310 licensed pesticide applicators. Participants provided detailed information on lifetime use of 50 pesticides at enrollment (1993–1997). Buccal cells were collected from 1999 to 2006. Relative telomere length (RTL) was measured using quantitative real-time polymerase chain reaction. We used linear regression modeling to evaluate the associations between specific pesticides and the logarithm of RTL, adjusting for age at buccal cell collection, state of residence, applicator license type, chewing tobacco use, and total lifetime days of all pesticide use.Results: The mean RTL for participants decreased significantly in association with increased lifetime days of pesticide use for alachlor (p = 0.002), 2,4-dichlorophenoxyacetic acid (2,4-D; p = 0.004), metolachlor (p = 0.01), trifluralin (p = 0.05), permethrin (for animal application) (p = 0.02), and toxaphene (p = 0.04). A similar pattern of RTL shortening was observed with the metric lifetime intensity-weighted days of pesticide use. For dichlorodiphenyltrichloroethane (DDT), we observed significant RTL shortening for lifetime intensity-weighted days (p = 0.04), but not for lifetime days of DDT use (p = 0.08). No significant RTL lengthening was observed for any pesticide.Conclusion: Seven pesticides previously associated with cancer risk in the epidemiologic literature were inversely associated with RTL in buccal cell DNA among cancer-free pesticide applicators. Replication of these findings is needed because we cannot rule out chance or fully rule out bias.     

Depression and Pesticide Exposures among Private Pesticide Applicators Enrolled in the Agricultural Health Study

Background

We evaluated the relationship between diagnosed depression and pesticide exposure using information from private pesticide applicators enrolled in the Agricultural Health Study between 1993 and 1997 in Iowa and North Carolina.

Methods

There were 534 cases who self-reported a physician-diagnosed depression and 17,051 controls who reported never having been diagnosed with depression and did not feel depressed more than once a week in the past year. Lifetime pesticide exposure was categorized in three mutually exclusive groups: low (< 226 days, the reference group), intermediate (226–752 days), and high (> 752 days). Two additional measures represented acute high-intensity pesticide exposures: an unusually high pesticide exposure event (HPEE) and physician-diagnosed pesticide poisoning. Logistic regression analyses were performed relating pesticide exposure to depression.

Results

After adjusting for state, age, education, marital status, doctor visits, alcohol use, smoking, solvent exposure, not currently having crops or animals, and ever working a job off the farm, pesticide poisoning was more strongly associated with depression [odds ratio (OR) = 2.57; 95% confidence interval (CI), 1.74–3.79] than intermediate (OR = 1.07; 95% CI, 0.87–1.31) or high (OR = 1.11; 95% CI, 0.87–1.42) cumulative exposure or an HPEE (OR = 1.65; 95% CI, 1.33–2.05). In analysis of a subgroup without a history of acute poisoning, high cumulative exposure was significantly associated with depression (OR = 1.54; 95% CI, 1.16–2.04).

Conclusion

These findings suggest that both acute high-intensity and cumulative pesticide exposure may contribute to depression in pesticide applicators. Our study is unique in reporting that depression is also associated with chronic pesticide exposure in the absence of a physician-diagnosed poisoning.     

Peripheral nervous system function and organophosphate pesticide use among licensed pesticide applicators in the Agricultural Health Study

Background: Evidence is limited that long-term human exposure to organophosphate (OP) pesticides, without poisoning, is associated with adverse peripheral nervous system (PNS) function.Objective: We investigated associations between OP pesticide use and PNS function by administering PNS tests to 701 male pesticide applicators in the Agricultural Health Study (AHS).Methods: Participants completed a neurological physical examination (NPx) and electrophysiological tests as well as tests of hand strength, sway speed, and vibrotactile threshold. Self-reported information on lifetime use of 16 OP pesticides was obtained from AHS interviews and a study questionnaire. Associations between pesticide use and measures of PNS function were estimated with linear and logistic regression controlling for age and outcome-specific covariates.Results: Significantly increased odds ratios (ORs) were observed for associations between ever use of 10 of the 16 OP pesticides and one or more of six NPx outcomes. Most notably, abnormal toe proprioception was significantly associated with ever use of 6 OP pesticides, with ORs ranging from 2.03 to 3.06; monotonic increases in strength of association with increasing use was observed for 3 of the 6 pesticides. Mostly null associations were observed between OP pesticide use and electrophysiological tests, hand strength, sway speed, and vibrotactile threshold.Conclusions: This study provides some evidence that long-term exposure to OP pesticides is associated with signs of impaired PNS function among pesticide applicators.     

Pesticide use and fatal injury among farmers in the Agricultural Health Study

Purpose

To assess whether pesticide use practices were associated with injury mortality among 51,035 male farmers from NC and IA enrolled in the Agricultural Health Study.

Methods

We used Cox proportional hazards models adjusted for age and state to estimate fatal injury risk associated with self-reported use of 49 specific pesticides, personal protective equipment, specific types of farm machinery, and other farm factors collected 1–15 years preceding death. Cause-specific mortality was obtained through linkage to mortality registries.

Results

We observed 338 injury fatalities over 727,543 person-years of follow-up (1993–2008). Fatal injuries increased with days/year of pesticide application, with the highest risk among those with 60+ days of pesticide application annually [hazard ratio (HR) = 1.87; 95% confidence interval (CI) = 1.10, 3.18]. Chemical-resistant glove use was associated with decreased risk (HR = 0.73; 95% CI = 0.58, 0.93), but adjusting for glove use did not substantially change estimates for individual pesticides or pesticide use overall. Herbicides were associated with fatal injury, even after adjusting for operating farm equipment, which was independently associated with fatal injury. Ever use of five of 18 herbicides (2,4,5-T, paraquat, alachlor, metribuzin, and butylate) were associated with elevated risk. In addition, 2,4-D and cyanazine were associated with fatal injury in exposure–response analyses. There was no evidence of confounding of these results by other herbicides.

Conclusion

The association between application of pesticides, particularly certain herbicides, and fatal injuries among farmers should be interpreted cautiously but deserves further evaluation, with particular focus on understanding timing of pesticide use and fatal injury.     

Maternal Pesticide Use and Birth Weight in the Agricultural Health Study

ABSTRACT

Studies examining the association between maternal pesticide exposure and low birth weight yield conflicting results. The authors examined the association between maternal pesticide use and birth weight among women in the Agricultural Health Study, a large study of pesticide applicators and their spouses in Iowa and North Carolina. The authors evaluated self-reported pesticide use of 27 individual pesticides in relation to birth weight among 2246 farm women whose most recent singleton birth occurred within 5 years of enrollment (1993–1997). The authors used linear regression models adjusted for site, preterm birth, medical parity, maternal body mass index, height, and smoking. The results showed that mean infant birth weight was 3586 g (± 546 g), and 3% of the infants were low birth weight (<2500 g). First-trimester pesticide-related tasks were not associated with birth weight. Ever use of the pesticide carbaryl was associated with decreased birth weight (?82 g, 95% confidence interval [CI] = ?132, ?31). This study thus provides limited evidence about pesticide use as a modulator of birth weight. Overall, the authors observed no associations between birth weight and pesticide-related activities during early pregnancy; however, the authors have no data on temporal specificity of individual pesticide exposures prior to or during pregnancy and therefore cannot draw conclusions related to these exposure windows. Given the widespread exposure to pesticide products, additional evaluation of maternal pregnancy exposures at specific time windows and subsequent birth outcomes is warranted.     

S-Ethyl-N,N-dipropylthiocarbamate Exposure and Cancer Incidence among Male Pesticide Applicators in the Agricultural Health Study: A Prospective Cohort

Background

The Agricultural Health Study (AHS) is a prospective cohort study of licensed pesticide applicators from Iowa and North Carolina enrolled between 1993 and 1997. EPTC (S-ethyl-N,N-dipropylthiocarbamate) is a thiocarbamate herbicide used in every region of the United States. The U.S. Environmental Protection Agency reports that EPTC is most likely not a human carcinogen; however, the previous epidemiologic data on EPTC exposure and cancer risk were limited.

Objectives

The purpose of this study was to examine cancer incidence and EPTC use in 48,378 male pesticide applicators enrolled in the AHS.

Methods

We estimated the rate ratio (RR) and 95% confidence intervals (CIs) for all cancers and selected cancer sites using Poisson regression. We assessed EPTC exposure using two quantitative metrics: lifetime exposure days and intensity-weighted lifetime exposure days, a measure that accounts for application factors that modify personal exposure likelihood.

Results

Among the 9,878 applicators exposed to EPTC, 470 incident cancer cases were diagnosed during the follow-up period ending December 2004 compared with the 1,824 cases among individuals reporting no use. Although EPTC was associated with colon cancer in the highest tertile of both lifetime exposure days and intensity-weighted lifetime days (RR = 2.09; 95% CI, 1.26–3.47 and RR = 2.05; 95% CI, 1.34–3.14, respectively) and the trend test was < 0.01 for both, the pattern of RR was not monotonic with increasing use. There was a suggestion of an association with leukemia. No other associations were observed.

Conclusion

In this analysis, EPTC use appeared to be associated with colon cancer and leukemia. However, given the relatively small number of cases in the highest exposure tertile, results should be interpreted with caution, and further investigations are needed.     

Pesticide use,allergic rhinitis,and asthma among US farm operators

Objective: The objective of the study is to examine associations between use of specific pesticides and lifetime allergic rhinitis and current asthma in US primary farm operators.

Methods: The 2011 Farm and Ranch Safety Survey data from 11,210 primary farm operators were analyzed. Pesticide use on the farm was determined using an affirmative response to the question of whether the operator ever mixed, loaded, or applied pesticides on their farm in the 12 months prior to the interview. Operators who answered “yes” were further asked about the specific trade name and formulation identifiers of the product they used and personal protective equipment (PPE) used. Data were weighted to produce national estimates. Adjusted prevalence odds ratios (PORs) were calculated using logistic regression. The referent group included operators who did not use any pesticides in the 12 months prior to the interview.

Results: Of an estimated 2.1 million farm operators, 40.0% used pesticides, 30.8% had lifetime allergic rhinitis, and 5.1% had current asthma. Insecticide and herbicide use were significantly associated with lifetime allergic rhinitis and current asthma. The use of 2,4-dichlorophenoxyacetic acid (POR = 1.5; 95% CI 1.2–1.9) and carbaryl (POR = 2.3; 1.4–3.7) was significantly associated with lifetime allergic rhinitis. Of operators using pesticides, 64.9% used PPE the last time they mixed, loaded, or applied pesticides.

Conclusions: Pesticide use was associated with lifetime allergic rhinitis and current asthma among farm operators. Further studies are needed to clarify the dose–response relationship between pesticide use and adverse respiratory health effects.     

Cancer Incidence among Pesticide Applicators Exposed to Permethrin in the Agricultural Health Study

Background

Permethrin is a synthetic pyrethroid insecticide widely used in agriculture, in public health, and in many U.S. homes and gardens.

Objective

In this study we evaluated the incidence of cancer among pesticide applicators exposed to permethrin in the Agricultural Health Study (AHS).

Methods

A total of 49,093 pesticide applicators were included in this analysis of the AHS, a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina. Detailed information on pesticide exposure and lifestyle factors was obtained from self-administered questionnaires completed in 1993–1997. Average length of follow-up since applicator enrollment in the cohort was 9.14 years. We used two permethrin exposure metrics: a) lifetime days applicators personally mixed or applied permethrin and b) intensity-weighted lifetime days (lifetime days weighted by estimated intensity of exposure). We used Poisson regression analysis to estimate relative risks (RRs) and 95% confidence intervals (CIs) for malignancies by tertiles of exposure.

Results

We found no associations between permethrin and all malignant neoplasms combined, or between permethrin and melanoma, non-Hodgkin lymphoma, leukemia, or cancers of the colon, rectum, lung, or prostate. We found elevated and statistically significant risks for multiple myeloma in the highest tertiles of both lifetime exposure-days (RR = 5.72; 95% CI, 2.76–11.87) and intensity-weighted lifetime exposure-days (RR = 5.01; 95% CI, 2.41–10.42), compared with applicators reporting they never used permethrin; these results are based on only 15 exposed cases. These findings were similar across a variety of alternative exposure metrics, exposure categories, and reference groups.

Conclusions

This study found no association with most cancers analyzed. Although the suggested association with multiple myeloma was based on a small number of cases, it warrants further evaluation.     

First-aid reports of acute chlorine gassing among pulpmill workers as predictors of lung health consequences

Workers in pulpmills can be exposed to a multitude of gases hazardous to respiratory function, the most common of which is chlorine gas. First-aid reports of acute gas overexposure incidents ("gassings") over an 8 year period were used to generate exposure data on a group of pulpmill workers whose respiratory function had been studied cross-sectionally in 1981 and 1988. Three hundred forty-eight incidents representing 174 workers were identified, 78% of these being treated solely by the first-aid attendant with the administration of O2 and cough suppression medication. Among 316 workers tested during a 1988 respiratory health survey, 78 had at least one chlorine or chlorine dioxide "gassing" incident. There was a significant decrease in the FEV1/FVC ratio (p less than .05) as well as increased risk for workplace associated chest symptoms in this group with at least one "gassing" incident. In an age- and smoking-matched analysis, among workers tested both in 1981 and 1988, there was a greater decline in FEV2/FVC ratio and MMF (p less than .05) in the "gassed" group than in the nonexposed group over the 7 year period of observation. These results emphasize the need for worker protection against accidental chlorine gas exposures.     

Agricultural Pesticide Usage and Prioritization in South Korea

This study aims to review agricultural pesticide usage and trends and to identify hazardous pesticides for regulation, in terms of public health, in South Korea. The authors collected data on usage and trends of agricultural pesticides through agriculture-related databases. Criteria from the US Environmental Protection Agency classification for carcinogenicity, World Health Organization classification for acute toxicity, and European Union prioritization list for endocrine-disrupting chemicals were used for the hazard categorization of identified individual active ingredients. Pesticides to be prioritized among all pesticides used in South Korea between 2007 and 2011 were selected by taking into account the volume of usage, toxicity, and epidemiological evidence. Annual agricultural use of pesticides has increased rapidly from the 1970s to 1990s in South Korea, but has declined since 2001. The quantity of pesticides used in 2011 was reported as 19,131 tons, and was comprised of 34.7% insecticides, 28.0% fungicides, and 27.1% herbicides. The 50 pesticides with the greatest volume of usage accounted for 82.6% of the total volume of pesticides used between 2007 and 2011, with the most-used active ingredient being machine oil, followed by mancozeb and then paraquat. Organophosphates were the most used among the top 50 pesticides. A total of 24 pesticides were selected for recommendation of intensive regulation in South Korea. In conclusion, the authors described the usage and trends of overall agricultural pesticides, which would serve as a fundamental step forward in managing pesticide in terms of public health. Intensive efforts are required for the prevention of potential health effects from the 24 identified pesticides.     

Parkinsonism Signs and Symptoms in Agricultural Pesticide Handlers in Washington State

Objectives: Examine associations between pesticide exposure and signs or symptoms of parkinsonism. Methods: Prior to the 2014 pesticide spray season, the authors examined 38 active pesticide handlers aged 35 to 65 (median: 43.5) who participated in the State of Washington’s cholinesterase monitoring program in the Yakima Valley, where cholinesterase-inhibiting insecticides are applied in fruit orchards. A movement disorder specialist assessed the workers using the Unified Parkinson’s Disease Rating Scale (UPDRS) motor subscore 3 (UPDRS3). Participants also self-reported work and medical histories, including the UPDRS activities of daily living subscore 2 (UPDRS2). The authors explored the relation between these scores and lifetime occupational pesticide exposure while accounting for age. Results: All participants were Hispanic men born in Mexico who had worked in agriculture for 4 to 43 years (median: 21 years, including 11 years applying pesticides, mostly in the United States). Ten participants (26%) reported difficulty with one or more UPDRS2 activities of daily living (maximum = 2), and nine (24%) had a UPDRS3 >0 (maximum = 10). The most common symptom and sign, respectively, were excess saliva (n = 6) and action tremor (n = 5). UPDRS2 and UPDRS3 scores were unrelated to the number of years applying pesticides, but UPDRS3, especially action tremor, was positively associated with living on or by a farm. Conclusions: Symptoms and signs of parkinsonism were absent to mild in this small sample of active workers who apply cholinesterase-inhibiting insecticides in Washington State, USA. Future studies should be larger and examine older, retired workers with greater cumulative exposure to agricultural pesticides at work and home, including other types of agricultural pesticides.     

Pesticide use and menstrual cycle characteristics among premenopausal women in the Agricultural Health Study

Menstrual cycle characteristics may have implications for women's fecundability and risk of hormonally related diseases. Certain pesticides disrupt the estrous cycle in animals. The authors investigated the cross-sectional association between pesticide use and menstrual function among 3,103 women living on farms in Iowa and North Carolina. Women were aged 21-40 years, premenopausal, not pregnant or breastfeeding, and not taking oral contraceptives. At study enrollment (1993-1997), women completed two self-administered questionnaires on pesticide use and reproductive health. Exposures of interest were lifetime use of any pesticide and hormonally active pesticides. Menstrual cycle characteristics of interest included cycle length, missed periods, and intermenstrual bleeding. The authors used generalized estimating equations to assess the association between pesticide use and menstrual cycle characteristics, controlling for age, body mass index, and current smoking status. Women who used pesticides experienced longer menstrual cycles and increased odds of missed periods (odds ratio = 1.5, 95% confidence interval: 1.2, 1.9) compared with women who never used pesticides. Women who used probable hormonally active pesticides had a 60-100% increased odds of experiencing long cycles, missed periods, and intermenstrual bleeding compared with women who had never used pesticides. Associations remained after control for occupational physical activity.     

Fertility and exposure to solvents among families in the Agricultural Health Study

Background

Several studies have reported associations between solvent exposure and reduced female fertility, but the evidence is inconclusive for male fertility.

Objectives

To investigate the impact of solvent exposure on subfertility among families of male licensed pesticide applicators in the Agricultural Health Study cohort.

Methods

The couples enrolled between 1993 and 1997. Cross‐sectional questionnaire information on work tasks was used to assess exposure to solvents. The data were limited to couples (wife aged less than 40 years) with an attempt at pregnancy in the last four years (n = 2112).

Results

Twenty eight per cent of the couples were defined as subfertile (not conceiving a pregnancy after at least 12 months of unprotected intercourse, regardless of whether or not a pregnancy ultimately occurred). Adjusted subfertility odds ratios (OR) for exposure to solvents were calculated with logistic regression. Female (OR 1.42, 95% CI 1.15 to 1.75) and male exposure to solvents (OR 1.21 (95% CI 0.93 to 1.57) for monthly exposure and 1.40 (95% CI 0.97 to 2.03) for daily or weekly exposure) were associated with subfertility. In farming, spouses may share or exchange jobs. To account for potential dual exposure, variables for parental exposure (either parent exposed or both parents exposed) were also defined. Both were strongly associated with subfertility (OR 1.62 (95% CI 1.20 to 2.17) and OR 2.10 (95% CI 1.22 to 3.60), respectively).

Conclusions

Solvents may impair fertility of either gender, though the evidence for female effects is stronger than for male effects.     

Cross-sectional epidemiological study of respiratory disease in Turkey farmers

This study was a cross-sectional epidemiological investigation of respiratory disease in farmers involved in the turkey growing industry. Pulmonary function tests and health history questionnaires were administered to a total of 95 turkey farmers throughout Minnesota. Respiratory symptoms were greatest during the winter months when exposure to environmental agents was highest. Prevalence of symptoms was higher for smokers, personnel who worked in hen barns, and for persons who had worked in the turkey growing industry for more than 10 years. Pulmonary function was found to decrease during the work day. Also, pulmonary function was lowest for personnel working in hen bars, and for persons who had been employed in the industry for more than 10 years. These data support the association between respiratory disease and exposure to the environment in confinement farm buildings. © 1993 Wiley-Liss, Inc.     

A Review of Pesticide Exposure and Cancer Incidence in the Agricultural Health Study Cohort

Objective

We reviewed epidemiologic evidence related to occupational pesticide exposures and cancer incidence in the Agricultural Health Study (AHS) cohort.

Data sources

Studies were identified from the AHS publication list available at http://aghealth.nci.nih.gov as well as through a Medline/PubMed database search in March 2009. We also examined citation lists. Findings related to lifetime-days and/or intensity-weighted lifetime-days of pesticide use are the primary focus of this review, because these measures allow for the evaluation of potential exposure–response relationships.

Data synthesis

We reviewed 28 studies; most of the 32 pesticides examined were not strongly associated with cancer incidence in pesticide applicators. Increased rate ratios (or odds ratios) and positive exposure–response patterns were reported for 12 pesticides currently registered in Canada and/or the United States (alachlor, aldicarb, carbaryl, chlorpyrifos, diazinon, dicamba, S-ethyl-N,N-dipropylthiocarbamate, imazethapyr, metolachlor, pendimethalin, permethrin, trifluralin). However, estimates of association for specific cancers were often imprecise because of small numbers of exposed cases, and clear monotonic exposure–response patterns were not always apparent. Exposure misclassification is also a concern in the AHS and may limit the analysis of exposure–response patterns. Epidemiologic evidence outside the AHS remains limited with respect to most of the observed associations, but animal toxicity data support the biological plausibility of relationships observed for alachlor, carbaryl, metolachlor, pendimethalin, permethrin, and trifluralin.

Conclusions

Continued follow-up is needed to clarify associations reported to date. In particular, further evaluation of registered pesticides is warranted.     

Respiratory diseases and pesticide exposure: a case-control study in Lebanon

STUDY OBJECTIVE: To evaluate the odds of being exposed to pesticides in asthmatic adults. DESIGN: A case-control study was performed in Lebanon. SETTING: People were approached when consulting physicians as outpatients. PATIENTS: Asthmatic patients and non-asthmatic controls in several Lebanese hospitals were interviewed. MAIN RESULTS: The study included 407 subjects from 10 medical centres. Any exposure to pesticides was associated to asthma (OR = 2.11 (1.47 to 3.02); p<10(-4)). Occupational use presented the highest association (OR = 4.98 (1.07 to 23.28); p = 0.02), followed by regional exposure (OR 3.51 (2.11 to 5.85); p<10(-4)). Results were confirmed by multivariate analysis, particularly for regional exposure (OR(a) = 2.78; p = 0.02) and house exposure (OR(a) = 2.17; p = 0.001). CONCLUSIONS: Results are comparable to those found in other studies; especially for occupational exposure. Pesticides toxicological effects may explain chronic respiratory symptoms and asthma associations found with all exposure types. Pesticide exposure was associated with asthma in Lebanese adults.     

Pesticide Use and Cutaneous Melanoma in Pesticide Applicators in the Agricultural Heath Study

Background

Melanoma rates continue to increase; however, few risk factors other than sun sensitivity and ultraviolet radiation (including sun exposure) have been identified. Although studies of farmers have shown an excess risk of melanoma and other skin cancers, it is unclear how much of this is related to sun exposure compared with other agricultural exposures.

Methods

We examined dose–response relationships for 50 agricultural pesticides and cutaneous melanoma incidence in the Agricultural Health Study cohort of licensed pesticide applicators, along with ever use of older pesticides that contain arsenic. Logistic regression was used to examine odds ratios (ORs) and 95% confidence intervals (CIs) associated with pesticide exposure adjusted for age, sex, and other potential confounders.

Results

We found significant associations between cutaneous melanoma and maneb/mancozeb (63 exposure days: OR = 2.4; 95% CI, 1.2–4.9; trend p = 0.006), parathion (≥ 56 exposure days: OR = 2.4; 95% CI, 1.3–4.4; trend p = 0.003), and carbaryl (≥ 56 exposure days: OR = 1.7; 95% CI, 1.1–2.5; trend p = 0.013). Other associations with benomyl and ever use of arsenical pesticides were also suggested.

Conclusions

Most previous melanoma literature has focused on host factors and sun exposure. Our research shows an association between several pesticides and melanoma, providing support for the hypotheses that agricultural chemicals may be another important source of melanoma risk.     

A Systematic Review and Meta-analysis of Childhood Leukemia and Parental Occupational Pesticide Exposure

Objectives

We conducted a systematic review and meta-analysis of childhood leukemia and parental occupational pesticide exposure.

Data sources

Searches of MEDLINE (1950–2009) and other electronic databases yielded 31 included studies.

Data extraction

Two authors independently abstracted data and assessed the quality of each study.

Data synthesis

Random effects models were used to obtain summary odds ratios (ORs) and 95% confidence intervals (CIs). There was no overall association between childhood leukemia and any paternal occupational pesticide exposure (OR = 1.09; 95% CI, 0.88–1.34); there were slightly elevated risks in subgroups of studies with low total-quality scores (OR = 1.39; 95% CI, 0.99–1.95), ill-defined exposure time windows (OR = 1.36; 95% CI, 1.00–1.85), and exposure information collected after offspring leukemia diagnosis (OR = 1.34; 95% CI, 1.05–1.70). Childhood leukemia was associated with prenatal maternal occupational pesticide exposure (OR = 2.09; 95% CI, 1.51–2.88); this association was slightly stronger for studies with high exposure-measurement-quality scores (OR = 2.45; 95% CI, 1.68–3.58), higher confounder control scores (OR = 2.38; 95% CI, 1.56–3.62), and farm-related exposures (OR = 2.44; 95% CI, 1.53–3.89). Childhood leukemia risk was also elevated for prenatal maternal occupational exposure to insecticides (OR = 2.72; 95% CI, 1.47–5.04) and herbicides (OR = 3.62; 95% CI, 1.28–10.3).

Conclusions

Childhood leukemia was associated with prenatal maternal occupational pesticide exposure in analyses of all studies combined and in several subgroups. Associations with paternal occupational pesticide exposure were weaker and less consistent. Research needs include improved pesticide exposure indices, continued follow-up of existing cohorts, genetic susceptibility assessment, and basic research on childhood leukemia initiation and progression.